An liquid crystal display (LCD) panel of an LCD is not a self-luminescent display element and thus requires a light source provided by a backlight module. In other words, the backlight module provides the brightness, uniformity of brightness and the visual angle (the aligning angle of light emission) required for displaying pictures. With regard to mechanical properties, the backlight module must be thin, lightweight and tolerant to shock. The properties of the backlight module directly influence the quality of the LCD, and thus, the backlight module becomes a very important component of the LCD screen.
Typically, the assembling process of the LCM (LCD module) entails assembling an LCD panel, a driver IC (integrated circuit), a backlight module and other components, fixing the sides of the LCM, comprising a metal frame, the LCD panel and the mold frame, by screws to enhance the whole structural strength. After examining the LCM for quality assurance, the manufacturing process of the LCM is finished.
Reference is made to FIG. 1, which illustrates a three-dimensional schematic diagram of an LCM in the prior art. The LCM 100 in the prior art comprises a metal frame 113 and an LCD panel 119, wherein a mold frame (not shown) is disposed in the metal frame 113, and the LCD panel 119 is disposed on the mold frame. A fixing rack 115, which is installed on a side of the metal frame 113, can be used to fix the LCM 100 onto other structures. In order to enhance structural strength, screws 111, such as self-tapping screws, are used to fasten the fixing rack 115, the metal frame 113, the mold frame and the LCD panel 119 together.
Reference is made to FIG. 2, which illustrates a three-dimensional schematic diagram of a side of the prior art LCM in the region 110 of FIG. 1. A self-tapping screw 111 is used to fasten the fixing rack 115, the metal frame 113, the mold frame (not shown) and the LCD panel 119 together via a hole 116 of the fixing rack 115 and a hole 118 of the metal frame 113 in the side of the LCM.
Reference is now made to FIG. 3, which illustrates a three-dimensional schematic diagram of another side of the prior art LCM in the region 130 of FIG. 1. A self-tapping screw 111 is used to fasten the metal frame 113, the mold frame (not shown) and the LCD panel 119 together via a hole 118 of the metal frame 113 in another side of the LCM.
For further discussion, reference is made to FIG. 4, which illustrates a three-dimensional cutaway diagram showing the mold frame and the metal frame of the prior art. The mold frame 117, which is formed from plastic with a mold, comprises a base 151, a sidewall 153 disposed on and surrounding the edge of the base 151 to define a space 155, and a supporting stand 157 disposed on the base 151 along an inner side of the sidewall 153 and disposed in the space 155, wherein the supporting stand 157 is used to support the LCD panel 119.
More specifically, the mold frame 117 can be disposed in a space 167 defined by the metal frame 113, wherein the metal frame 113 comprises a bottom plate 161, a sidewall 163 disposed on and surrounding the edge of the bottom plate 161 and an upper frame 165 disposed on the sidewall 163, wherein the bottom plate 161, the sidewall 163 and the upper frame 165 define a space 167. When the mold frame 117 is disposed in the space 167 of the metal frame 113, the sidewall 163 of the metal frame 113, the sidewall 153 of the mold frame 117 and the supporting stand 157 are fastened securely together by the screw 111.
Reference is made to FIGS. 5(a) and 5(b), which illustrate cross-sectional diagrams of the prior art LCM along the line A-A′. Reference is made to FIG. 5(a), which shows that the self-tapping screw may generate a transient torque 121 when the screw is used to securely fasten the metal frame 113 and the mold frame 117 together. In FIG. 5(b), the metal frame 113 is more rigid, so the torque doesn't influence it. However, the mold frame 117 is less rigid and constrained in the horizontal direction due to the metal frame 113, so the torque 121 of FIG. 5(a) causes the mold frame 117 to generate a local deformation along the vertical direction, as shown in the region 125. The deformation of the mold frame 117 in the region 125 may result in interference on the LCD panel 119. Therefore, when a user presses a corner of the LCM 100 and wiggles it, ill phenomena such as oppressive light leakage and ripple may appear on the LCD panel 119.
The local deformation in the mold frame during the assembling process of the LCM has mainly been addressed by two methods. One method entails either applying a flexible material to the components in the LCM in order to decrease the torque or strengthening the molded frame by making it more rigid. The other method involves releasing the torque of the screw or loosening the screw by about a quarter turn during the stage of examining the LCM, after which time it is re-tightened. However, releasing the torque of the screw may disengage the screw completely from the mold frame. Furthermore, loosening and re-tightening the screw may wear down the threads of the screw fastening into the mold frame, causing some doubts about the structural integrity of the LCM and hence increasing the load of LCM inspectors.
Accordingly, it is indeed necessary to provide a molded frame for LCM, so as to improve the ill phenomena of severe light leakage and ripple apparent on the LCD panel due to the local deformation of the molded frame resulting from the torque generated by turning screws in.